The invention relates to a high-pressure discharge lamp provided with a discharge vessel which is enclosed with intervening space by an outer envelope and which is provided with electrodes between which a discharge extends in the operational condition of the lamp, while each electrode is connected to a relevant current supply conductor, and provided with an igniter circuit which comprises a voltage-dependent capacitor and a resistor.
A lamp of the kind mentioned in the opening paragraph is known from JP-A-2-165553 (1990). In the known lamp, which is suitable for operation in series with a stabilizer ballast on an AC voltage supply source, the capacitor is arranged in the outer envelope. The known lamp comprises a bimetal switch in the electrical connection between the voltage-dependent capacitor and the current supply conductors. Heat generated by the lamp after ignition ensures in this case that the bimetal switch opens, so that the direct electrical connection is broken and the operation of the igniter circuit is thus ended.
It is attractive to arrange the capacitor in the outer envelope because of a comparatively simple lamp manufacturing method, inter alia because there is comparatively much space available there, in contrast to, for example, the lamp cap. Breaking of the electrical connection by the bimetal switch involves a risk of residual charge remaining on the capacitor. Without further precautions, this will lead to internal degeneration of the capacitor, resulting in short-circuit through the capacitor. The comparatively high temperature at which the capacitor is in the operational condition of the lamp plays a detrimental part here. To prevent this, a comparatively high-ohmic resistor is included in the igniter circuit so that residual charge can flow away from the capacitor.
A disadvantage of the known lamp is the use of an additional component in the form of the resistor in the igniter circuit. This raises the manufacturing cost both on account of a higher complexity of the manufacture and on account of a rise in the reject percentage during manufacture. A further disadvantage is that the use of the additional component seriously hampers an automation of lamp manufacture. This accordingly leads to a more expensive manufacturing method for the lamp.